The present invention relates to an arrangement for filling fuel tanks of motor vehicles, especially of motorcycles, with a cylinder secured at the tank walls, surrounding the tank filling opening and projecting into the tank, with a short pipe piece arranged to be extended out of and retracted into the cylinder, with a cover for closing the filling opening when the short pipe piece is retracted,and with a seal for avoiding the discharge of fuel vapor-air-mixture during the filling operation.
Such an arrangement is disclosed in the German Pat. No. 27 18 161. The short pipe piece is thereby adapted to be extended and retracted by threaded means. In order to prevent a discharge of fuel-air-mixture by way of the threads, a sealing ring is provided in a groove in the cylinder which abuts against the outer thread of the short pipe piece. During the operation, the tank must be vented. Without such venting, an excess pressure builds up in the tank, for example, when being warmed up, which would lead to the fuel being forced out during the opening of the closure cover and with a filling level above the lower end of the cylinder. However, fuel vapors are given off to the atmosphere during the operation of vented fuel tanks. For this reason vented tanks have already been prohibited in part by official regulations such as the California "Fuel Pipe Regulations".
A filling arrangement for a fuel tank is disclosed in the British Pat. No. 150,544 which includes a short pipe piece that is slidable in a cylinder arranged in the tank. For stopping the short pipe piece in the extended position during the filling of the tank, a nose is arranged at the lower end of the cylinder which engages in a longitudinal groove of the short pipe piece when the latter is extended, whereby after ths short pipe piece is pulled out and rotated, the nose engages the same from below. With this prior art arrangement, an existing excess pressure in the tank would lead with a high filling level, to the fuel being forced out during the opening of the closure cover. Therebeyond, the tank interior is in communication with the free atmosphere during the filling of the tank by way of the longitudinal groove so that fuel vapors can escape into the atmosphere during the filling operation.
The object of the present invention resides in providing an arrangement of the type described above, by means of which a discharge of fuel is prevented when opening of the closure cover with a high filling level, and more particularly with unvented fuel tanks.
The underlying problems are solved according to the present invention, in that the cylinder includes at least one aperture, through which the area above the filling level in the tank is adapted to be connected with the atmosphere when the short pipe piece is retracted, and the seal is arranged in such a manner that with an extended short pipe piece the connection between the aperture and the free atmopshere is closed off.
Thus, an arrangement for filling a fuel tank by means of a filling nozzle with a gas suction device is created by the present invention, and more particularly up to a maximum possible filling level, whereby a seal assures that during the filling no fuel vapors can leave between the pulled out short pipe piece and the guide cylinder. Therebeyond, however, the arrangement according to the present invention is intended for nonvented fuel tanks, i.e., for fuel tanks, especially for motorcycles, with a pressure-holding system so that also during the normal operation of the vehicle, no fuel vapors can be given off to the atmosphere, at least during normal operation. Of course, a safety valve is provided in the nonvented fuel tank in case of an excessively large excess pressure.
Therebeyond, the arrangement according to the present invention can be handled in a simple manner and can be manufactured with the use of relatively inexpensive materials such as plastic materials.
According to another feature of the present invention, a closure cover is provided at the inner end of the short pipe piece which is spring-loaded in the closing direction and opens into the tank. Such closure lid is of advantage because it additionally prevents a fuel discharge during the opening of the closure cover in the manner of a check valve and prevents an overfilling of the tank also with normal filling nozzles, i.e., with filling nozzles having only a cutoff contact at the free end of the discharge pipe. This is so as shortly before the maximum filling level is reached during the filling operation, the spring-loaded lid begins to close so that the filling level rises reltively rapidly in the short pipe piece and therewith actuates the contact, whereupon the fuel present in the short pipe piece flows slowly into the tank interior by way of the lid.
According to a still further feature of the present invention, a bayonet connection is provided for stopping the short pipe piece, whose ring groove is arranged at the upper end of the cylinder while the claws of the bayonet connection are arranged at an annular collar at the short pipe piece and the annular collar forms the seal by abutment at one of the side surfaces of the annular groove. This arrangement permits to integrate the seal into the bayonet connection for stopping the short pipe piece in the extended position, as a result of which the seal can be made by simple manufacture and with small space requirements.
According to still another feature of the present invention, the short pipe piece is spring-loaded into its extended position by a spring which is supported, on the one hand, at the cylinder and, on the other, at the lid. This represents an advantageous construction of the present invention because the spring not only facilitates the pulling out of the short pipe piece out of the cylinder, but additionally it prevents rattle noises as the short pipe piece is pressed against the closure cover during the operation of the vehicle.